1. Field of the Invention
The present invention relates generally to swimming pools and more particularly to sealing apparatus for closing off the sidewall opening of a skimmer when the swimming pool is closed for the winter season, for example. It is common to employ one or more skimmer devices in the sidewalls of swimming pools, hot tubs and the like to permit surface water to be drawn off by a pump, filtered at a remote location and returned to the pool through one or more return ports. When the pool is closed during the winter season, it is sometimes desirable to maintain a level of water in the pool for structural purposes. In such cases, it is necessary to close off the skimmer to prevent backflow of water through the skimmer conduit to the filtration equipment so as to prevent damage to the pipes and filtration equipment due to freezing during the cold winter months.
2. Description of the Prior Art
One common way of closing off the skimmer is to employ an elongated plug-like element, marketed under the trademark "GIZMO". The plug element is threadably secured within the floor of the skimmer body to seal the conduit communicating with the pump and the filtration equipment. U.S. Pat. No. 4,913,810 to Jerry Hodak discloses a system for closing off a skimmer opening by providing a cover panel for securement onto an extra gasket frame which is specially fitted between the pool sidewall and the skimmer face plate. In order to use the device of U.S. Pat. No. 4,913,810, it is first necessary to physically remove the face plate from the skimmer and pool sidewall in order to install the special gasket frame therebetween. Needless to say, this requires extra labor and expense which may cause the average swimming pool owner to choose not to employ such a retrofit. The extra plate may also cause leakage if not properly installed. The invention disclosed in U.S. Pat. No. 5,285,538 to Frank J. Hodak, co-applicant herein, is directed to a sealing assembly for a skimmer opening which does not require the extra gasket frame called for in the above-cited, commonly owned patent, and therefore is much more reliable and easier to install. The cover member of the aforementioned U.S. Pat. No. 5,285,538 cooperates with the face plate of the skimmer to provide a much improved seal than heretofore possible in the prior art.
The present invention represents an improvement over U.S. Pat. No. 5,285,538 which is incorporated herein by reference. As stated, the sealing device of the aforesaid U.S. Pat. No. 5,285,538 provides an excellent seal around the skimmer opening. A problem develops, however, after the winter season when the water level has risen above the skimmer opening. In this condition, the water pressure acting against the face of the sealed skimmer cover forces the cover tightly against the skimmer face plate. In addition, algae growth over the pool sidewall and skimmer cover usually occurs over the dormant winter period, creating a slippery surface on the cover. The force of the water pressure, coupled with the slippery surface, as well as the tight snap fit around the periphery of the skimmer face plate, makes the skimmer cover of U.S. Pat. No. 5,285,538 difficult to remove from the face plate.